Refractor



Sli

I Patented @et l5, i923 einem PATENT orifice.

WILLIAJVI A. DOREY, OF NEWARK. OHIO. ASSIGNOR TO HOLOPHANE GLASS COMPANY, INC., 0F NEW YORK. N. Y.. A CORPORATION OF NEW JERSEY.

REFRACTOR.

Application filed February 27, 1920. Serial No. 361,?34.

.To all whom t may eminem:

Be it known that l\\'n.1.i.\u Donar, a. citizen of the United States, and resident opt Newark, in the county ot'llliehinzcr and State oi Ohio, haveinvented certain new and useful improvements in llelraetors, of which the following is a specification. I

The object of my invention is to construct a refraetor for light raya, especially adapted for automobile lamps and the like which Will direct the light rays iu de linitc zones, complying with the,requirel'uents ot' modern regulations with reference to such relracting lensea.. This object. is obtained by eonstructing a plate which will produce a broad beam of light ot' maximum depth at one extremity and ay minimum depth at the other extremity. The inventioii has been developed `["or use. principally wtlr automobile head-lights but it; has a range ol use other than this, and can be used for any lighting specification requiring a reti-actor to t'ullill the conditions set forth. e

Fig. l is the back view of an automobile plate embodying my invention. Fig. 2 is a horizontal cross/section oi Fig'. t on the line 2/2. Fig. 3 is a diagrannnatic. exposition ot' the spot produced by an unmodilied headlight on a vertical Screen. Fig. 4t is a diag lanimatie exposition ol' the spotI produced on a Vertical screen by a headlamp emploiyV ing my invention. Fig'. -is a vertical crossw section of a plate..embodying a modilieation of the invention. lfig. (3 is a horizontal. cross-Section ot' a plate embodying a l'urther modification thereof.

This construction, as hereinafter planted, will enable the approaehin; driver to pass with Safety and todo so he must he protected againet 2elare from a position 200 feet in front to the position of passing. At the same. time this construction will enable the driver behind the lamps to LQecthe t'ull width ot the road one hundred teet in t'ront .ot him and also discern laree objects` direetlv iu l'ront or to the right side ot the road. the direction in which he must. turn to pass the approaching driver at distance ot two hun dred feet or more. "fhediagram ot the spot produced by a bare headlamp with parabolic retiector, Figure 3, can the problem involved. l

lt it be assumed that the light source is spherical. the circle 3 re]f)resents they EspotJ ol' light produced on al vertical Screen at. om hundred teet distance by the' widest Vcone ot lightvt'rom'anunmodified headlamp and the circle l represente the spot from the narrowest cone. The wideet cones ot' reflected light will originate at the center of the reflector and the narrowest.cones of light will originate at the perimeter-of the reflector. In any plane thruthe axis of the reflector the spread ot' the cones of'light proeeeding` from the reflector will decrease as the edge of the reflector is api'n'oached.

be4 used to indicate It the light source be in tocus the spots or images from all the cones of light will be lSubstantially coiicentrie. Since all oones will contribute to the illumination within bound-.inv l, that portion ot' theepot will be brightest and since Alewer cones eontrilnite to thev illumination as they boundary li is approached the intensity of the light will drop an boundary 3 is approached. The headlamp isassumed to be mounted three and a haltI teet above the roadway and tilted downward two feet. per one hundred feet. Under these conditions the axis of the beam will be one and one-half feet above the road way at a distance ol' one hundred feet. The

glarel line indicated in Figure 3 is tive feet V above the road level and will represent the approximate level ot' the eyes of an ap proaehiuxg4 driver.

ln order that/an approaching driver may pass with sa'l'ety he should be protected as well au possible against glare from .a posi tion two hundred feet. in t'ront to the position ol passing. The intensity of the -beam at point 7, Figures 3 and '4, will give a. fair masure of the glare before the driver has turned out Vlor passino. The intensity at the point S will give. a fair measure of the glare at'ter the driver has turned out tor passing. Point' 9 represents that point in the beam which will Strike. the roadway two hundred feet directly in front ot the car. The highest possible illumination should be obtained at thistpoii'n; eonsiatent with a; sutlicient sup- Miti vsuch cones to solve the problem.

pression of glare at point 7. Point l() represents a point in the road, seven feet to the right ot the vertical axis of the lamp and one hundred feet in front ot the car. Considerable degree of illumination is required at this point so that ditches, curbs and other obstacles may be easily discerned when the driver is turning' out to pass an approachinzc` driver. The intensity secured vat points S and 10 are a fair measure oi the road ilhunination secured. At the same time however, it is desirable on account of lett hand turns to have a. fairlyv goed road illumination one hundred feet in front of the car and to the lett ot the axis.

It will be noted in Figure 3 that the more intense portion oi the beam lfalls on point i.) and therefore the unmoditicd beam will ,cire sat'istactory illumination at that point. The extreme edge ol the beam falls on point l() so the illumination will not. be suti'icient at that point. 'lhe unmodified. beam is .not wide enough to illuminate the whole width ol the rod.

It will be noted that while point 7 lies without the most intense portion ot the beam. it is close enough to the axis oi' thc beam to receive light from a major portion ol the wider cones proceedim;- t'rom the replate showiuin Figs ,l and in which AB is a concave cylindrical surface which forms in conjunclionwiththeouter surl'ace otl the plate a plano-concave lens. At the. point (l this concave surlace has been stepped so as to 'reduce the weight ot the glass. Bl) is a convex cylindrical surface which in conjunction with the outer surface o't' the plate Aforms Aa plano-convex lens. The convex surface is stepped at the point ll so as to reduce the weight oi" the glass.

'lherays ol light l to (i. shown on Figs. l and L). represent the axes ot typical cones ot light. reflected from the 'retltwtor used with such plates. The following exposition will show how the lenticular surt'aces operate ou These cones will be substantially normal to the .trout tace ol' the plate. The points where 2 and 5 strike the plate lie in planes which are parallel to the front t'ace and these rars will be emitted at Q and 5a without chantre in direction. cepting rays 1 and t5 are inclined so that such rays are deviated toward the lett and emitted in directions la and t5, @wing to the curvature of the inner surfaces intermediate rays between l and will be deviated to a graduallyv lessening degree as f2 is approached. In the saaie way The interior surfaces inter-` rays between G and 5 will be deviated to a lgradually lessening degree as 5 is approached. The interior surfaces intercepting rays 3 and 4 are inclined so that the)r are. deriated towards the right and emitted in directions 3 and 4, Intermediate rays between 3 and 2 and between 4. and will be ydeviated to a gradually lessening,r degree as t2 and 5a are approached.

The lspot. actually produced on a vertical screen by a headlamp when covered with the plate is in the form ot' a horizontal arrow head with the point towards the lett and the barb toward the right. A band runniingr from the point to the center oiE the base is brightest. The surrounding portion of the spot is less definite and ot much less intensity. This torni of spot meets m'odern specifications tor headlight-ing very satistactorily.

Fig'. el is a diagrammatic Yiew similar to Fig. 3. The arrow shaped spot 3d represents the eXtreme limit ot the combined image obtained from a headlamp when covered with the plate. The band ld represents 'the brightest portion olE the combined spot produced with a headlamp. and this plate. The mounting height and tilt ot lamp and other. conditions arethe same as thosz assumed in Figure 3.

.lt will be noted that the bright part of the beam has been spread laterally so as to gire goed illumination at points between 9 and l0 and also at corresponding points to the lett -of the axis. The plate spreads the brightest part'y of the beam so that good illamination is obtained across thewhole"sur-l tace ot the road. Point 7 will receive light from only a small portion ot the wider cones. Therefore the lamp with plate will give great reduction in glare abt distant points in comparison with the unmodified beam Fig. 3. Point 8 lies entirel7 wit-hout the beam, therefore. the lamp with plate will give great reduction in glare for the approaching driver after he has turned out tor passing. In aufY particular type of lamp the beam should be depressed or the candle power ot the lamp lowered until the desired minimum values are reached.

rlhe action ot the plate as described is to bend the central portion o'f the bea-m to one side. and the side portionsof the beam to the. opposite side. Referring to Fig. 2 if the plane surface be placed against the headlamp instead ot the curvedsurface the resultant'. action on the projected light rays will be exactly the same and such use comes within the scope of mv invention.

Fig. 6 shows a modifica-tion of m. invention in which the vconcave cylindrica surface AB on the interior combined with the ooncave cylindrical surface J en the exterior torina a conc-ave lens and the solares aart @ce El? en interior wallet-he described.

cylindrical surface JK on the exteriolsforms a convex lens. The lens surfaces are stepped atlE. L. M. and N to reduce the thickness of the glass. The light rays l-6 represent the axes of typical projected cones of light and will be substantially normal to the generalv surface of the plate.v

The resultant action on the projected light rays will be exactly the same as in the type Such a construction comes within the scope of my invention.

The form of lens described is especially adapted for use with tilted headlamps. In case it be desirable to use, the headlamp in a horizontal position the plane surface may be set atan inclination to refract the light downward or may be broken up into plane surfaces at varying inclinations so as to modify the vertical distribution of the projected light rays as desired. Thus' in Fig. 5 I show a vertical cross-section of such a modification in which the surface H'is provided with vertical cylindrical elements such as are shown in Fig. 2. On the opposite side of the lens the plane surfaces .G are inclined with reference to the general plate level. Light rays proceeding from the reflector such as 7, 8, and 9 will be deviated horizontally by the cylindrical element ll, pass through the lens and be depressed downward by the prisms Gr in directions smh as 7, 8a and 9a. The degree of depression produced by the prisms G will depend on `their inclination with reference to the general lenssurface.

R In the claims I have used the expression elements7 to designate the different portions of the lens. By this is meant a single portion operating in the manner shown or 1. A light transmitting cover for a rel tractor divided vertically into two substantially equal sections, one section comprising similar vertical elements forming a cylindrical plano convex lens adapted to converge parallel rays incident thereon, and the second section comprising similar Vertical elements forming a cylindrical plano concave lens adapted'to diverge parallel rays incident thereon, the relation of elements being such that the total beam projected will be substantially apioid.

2. A flat light transmitting refractor one face being divided into two equal sections, one section being a concave cylindrical surface and the other section being a convex cylindrical surface, the axis of each cylinder being parallel with the central division line and lying in a plane normal to the lcover'and intersecting the c'orrespending section of the cover, the opposite face having n iwlurality of horizontal prisms formed to depress the beam.

3. A iiat light transmitting cover for a refractor divided into sections by a 1in-e through its center, one section being a cylindrical plano-convexlje'iis and the other being a cylindrical lano-concave lens, the axis of each cylinder eing parallel with the central division line and lying in a plane normal to the cove-r and intersect-ing the corresponding section of the cover. y

igned at Newark in the county of Lickand State el' Ohio February A. D. 1920.

WILLIAM A.VDOREY.

cover for a lng 

